Sand Mix Inter layer to Control Reflective Cracking in Hot-Mix Asphalt Overlay

This study examines the behavior of traffic-induced reflective cracking in hot-mix asphalt (HMA) overlays with and without a sand mix interlayer and evaluates the interlayer's performance to control reflective cracking. A three-dimensional finite element (FE) model was built for a typical HMA overlay constructed over a jointed concrete pavement. A linear viscoelastic model and a bilinear cohesive zone model were incorporated into the FE model to characterize continuum and fracture behavior of the HMA overlay and the sand mix interlayer. One pass of an overload was applied to force reflective cracking development. Then the reflective cracking resistance capacity of the HMA overlay was quantified with a limit-state load that resulted in macrolevel reflective cracking in the entire cross-sectional area of the HMA overlay. This study found that the sand mix interlayer enhanced the reflective cracking resistance capacity of the HIVIA overlay by a factor of 1.17 to 2.45 because of the sand mix's higher fracture toughness. The performance benefit was more dominant at an early service life of the HMA overlay. As the elastic modulus of a base layer decreased, the reflective cracking potential was found to increase, but the sand mix interlayer was still effective in retarding reflective cracking.